Re: [Xen-API] value of timestamp from API event.from() is always '0'

[tony_caotong@xxxxxxx]

Now my solution is that using two threads, one call event.next() and 
return immediately, and another deal with the events returned.
So I can get messages with timestamps, but cannot get the events history.

Maybe there is a bug under XenServer 6.2 ?

-----------
Cao Tong

On 09/17/2015 09:42 PM, Dave Scott wrote:
> > On 17 Sep 2015, at 13:39, Uli Stärk <Uli.Staerk@xxxxxxxxxxxxxx> wrote:
> >
> > Hey Tony,
> >
> > I've seen this too. I don't know what the events.from was designed for. I've seen 
> > XenCenter using it for a "fast"-sync with the pool, and features some kind of 
> > logging (see id=0, class=message). I think you can safely skip all events with id=0 and 
> > accept the ts=0 as given :)
> I’ve cc:d Jonathan Ludlam, who built the `event.from` mechanism — he can 
> probably describe the fine-detail.
>
> The main semantic difference between `event.next` and `event.from` from my point-of-view is 
> that `event.next` reads from a fixed-space queue of object state snapshots which can easily 
> overflow, while `event.from` fetches the *current* state of all objects which have changed 
> since your last update. If you want to display the most up-to-date information — like 
> XenCenter does — then `event.from` is the way to go. We also had a lot of problems 
> with the `event.next` queue overflowing, especially under heavy load (e.g. while starting 
> lots of VMs). This caused `event.next` to return a lot of exceptions, which means you have to 
> re-register for events and poll the current state of the objects again, adding even more load 
> to the overloaded system.
>
> I recommend using `event.from` if you can :-)
>
> Cheers,
> Dave Scott
>
>
> > I handle the pool syncing a little bit different, which is slower, bit a bit 
> > more straight forward:
> > 1. event.register(*)
> > 2. foreach($obj_types as $type) $type.get_all()
> > 3. while($running) event.next()
> >
> > Greetings
> > Uli Stärk
> >
> > -----Ursprüngliche Nachricht-----
> > Von: xen-api-bounces@xxxxxxxxxxxxx [mailto:xen-api-bounces@xxxxxxxxxxxxx] Im 
> > Auftrag von tony_caotong@xxxxxxx
> > Gesendet: Mittwoch, 16. September 2015 04:39
> > An: xen-users@xxxxxxxxxxxxx; xen-api@xxxxxxxxxxxxx
> > Betreff: [Xen-API] value of timestamp from API event.from() is always '0'
> >
> > Hi all,
> >
> >      My xenserver version is 6.2
> >      When I fetch logs from API function event.from(), the value of each 
> > timestamp field is always '0.' .
> >      Instead of event.next(), it is fine.
> >      Could anyone give me some advices ?
> >
> > --
> > -----------
> > Cao Tong
> >
> >
> >
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